No subject

You can either try and fix sendmail (or as Ben says, replce it with
somethig easier to configure like exim or postfix) or persuade
fetchmail to deliver mail locally by calling sendmail directly
(like the MUA example above)
A quick glance at the man page suggests that
fetchmail -m "/usr/sbin/sendmail -oem -f %F %T"
would be approprate if you don't want to wrestle with sendmail.
--
Mike Bristow, seebitwopie